1. Field of the Invention
The present invention generally relates to frame relay networks, and more particularly to a user-configurable frame relay network that may be reconfigured under the control of a user or user equipment, while at the same time providing all the benefits of a service provided frame relay network.
2. Discussion of the Related Art
As is known, frame relay is a stream-lined method for packet switching that operates at the data link layer of the OSI model, and has significantly less overhead than traditional packet switching techniques. By way of background, the provision of digital communications paved the way for technology referred to as packet switching, which is carried out by dividing communicated data (where data broadly denotes voice, data, video, etc.) into discrete units known as packets. Packets may be time multiplexed to allow multiple users or end points to communicate across a common line.
As is further known, X.25 is a popular protocol used for controlling and managing packet switched communications. It utilizes call-control packets to set-up and clear virtual circuits, and carries these call-control packets on the same channel and same virtual circuit as data packets are carried. In this regard, X.25 utilizes in-band signaling. However, X.25 demands considerable overhead, and therefore sacrifices data throughput In this regard, X.25 protocol requires an acknowledgment packet to acknowledge the reception of each packet at every intermediate node along a transmission path or virtual circuit. State tables must be maintained, at each intermediate node, for each virtual circuit to deal with the call management and flow control/error control aspects of the X.25 protocol.
The further development, however, of packet switching technologies into frame relay transmissions represented a significant advance in the state of the art. Frame relay technology makes the assumption that the integrity of a communication link will remain intact. Using this assumption, frame relay does not require individual acknowledgments from each intermediate node along a communication path, that a particular data packet has been successfully received. It also eliminates the overhead associated with the maintenance of state tables for transmissions. As a result, frame relay technology realizes significantly improved throughput over that realized by X.25 protocol. The down side of frame relay is that data packets do occasionally get lost, discarded, or otherwise unsuccessfully transmitted. Any type of error control imposed on frame relay, must be implemented from a higher layer (e.g., the transport layer) of the OSI model.
In the early days of frame relay technology, service provided networks did not exist. Therefore, users of frame relay technology typically had frame relay user equipment interconnected by way of a leased line, for example. By way of illustration, a corporate enterprise having geographically dispersed offices wishing to intercommunicate via frame relay may have purchased a leased line from a communication service provider, which leased line was dedicated to run between the frame relay equipment at each end. This, however, was a relatively costly solution, as it required the purchase of a dedicated line, which may not be fully utilized if there were only intermittent communications between the two end points.
The proliferation of frame relay technology, however, led to the creation and provision of frame relay service networks by service providers. As is known, a frame relay service provider network effectively comprises a mesh of interconnected nodes that can be variably configured to provide a communication path between a plurality of end points. Returning to the previous example, a geographically dispersed corporate enterprise may intercommunicate using frame relay technology by purchasing from the service provider what are known as permanent virtual circuits. A permanent virtual circuit is a configuration of various intermediate nodes in the frame relay service network which are dedicated to direct communications between a first end point and a second end point along a particular path. The service provider will typically establish permanent virtual circuits, within a frame relay network, in a way that evenly distributes data traffic and minimizes traffic congestion. Therefore, as additional users/communicating end points are added to the frame relay service network, the service provider may alter or otherwise reconfigure various permanent virtual circuits. However, it will communicate any such changes to the users at the end points.
Data link connection identifiers (DLCI's) are numbers that identify the various intermediate nodes between end points of a frame relay communication link. DLCI's identify the various intermediate nodes and therefore identify the particular communication path between end points. As is known, the provision of permanent virtual circuits simplifies the error control mechanisms for data transport utilizing frame relay technology, as opposed to communication links which are based on IP addresses and routers (where the communication path may vary from packet to packet). However, a disadvantage of the service provided frame relay service network is that, although it is reconfigurable, it is not dynamically reconfigurable. Stated another way, it is not user configurable. Rather, once a permanent virtual circuit is established by the service provider, it remains fixed unless and until the service provider reestablishes a different communication path. Therefore, if a user identifies a fault in the communication link, the user must generally report that fault to the service provider and wait for the service provider to setup an alternative route of communication. This is extremely costly in instances where the need to transport data is time sensitive.
Accordingly, there is a need to address this and other related shortcomings in the art, by providing an enhanced medium for communicating in accordance with frame relay technology, that is dynamically user configurable.